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LIBRARY OF CONGRESS. 



Shelf i.MM. 

UNITi]|>STATES OF AMERICA. 







BK^l? # ^'- '^4 -^.-i^ ,-'■:;':. -: , #• 




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CAR LUBRICATION. 



. r^ BY 

W. EXHALL, B.S.. M.E. 







NEW YORK: 

JOHN WILEY & SONS, 

53 East Tenth Street. 
1891. 







Copyright, 1891, 



JOHN WILEY & SONS. 



Robert Drummond, 

ElectrotypeVt 

444 & 446 Pearl Street 

New York. 




^- 



Ferris Bros., 

Printers, 

826 Pearl Street, 

New York. 



PREFACE. 



Some years ago the subject of car lubrication became 
one of much interest to the writer, and, when attempt- 
ing to acquaint himself with the laws influencing suc- 
cessful practice, he was surprised to find how very little 
information, either of a theoretical or practical nature, 
could be obtained. The accompanying pages are not 
presented as a solution of the question, or as contain- 
ing any important original research, but rather in the 
hope that some of the knotty problems which were 
then presented for solution may be made clearer. 

The laws of friction, as accepted until recently, have 
by later experiments been limited in their application, 
if not confined entirely, to solids in contact. It is at 
least certain that they will not apply in any way as the 
laws governing the friction of solids separated by a 
lubricant. Prof. Thurston's *• Friction and Lost Work,'* 
and the experiments of Mr. Woodbury with those of 
Mr. Tower, are quoted, and several others to a limited 
extent — to whom, it is hoped, proper credit has been 
given. 

It is desired that these few words may stimulate 
further thought, and in that way result in a more satis- 
factory solution of the problem. 

The Author. 

Altoona Machine Shops, Mav, i8qi. 



CAR LUBRICATION. 



CHAPTER I. 

INTRODUCTION. 

The subject of car lubrication is wholly dependent 
upon the conditions which influence friction, either in- 
creasing or decreasing the resistance according to the 
design and proportions of the different parts, as well as 
by the care and attention which are given to the lubri- 
cation proper. There is hardly any other one branch 
of railroad engineering so dependent upon empirical 
laws, and but few where the heretofore accepted laws 
of friction are at such variance with practice. 

The widely taught law that friction is independent 
of the extent of surface in contact, but varies only with 
the pressure, is about ready to be placed among the 
archives of ancient scientists. The pressure inferred in 
this relationship is that exerted over the whole surface, 
and not per square inch — that is, a surface one square 
foot in area exerting a pressure of one pound per square 
inch would require the same force to move it over a rub- 
bing surface as it would if made of one square inch in 
area exerting a pressure of 144 pounds per square inch. 
The extent of surface in contact was supposed to have 
no effect upon the force or work of friction necessary 
to move one body upon another, and consequently 

I 



2 CAR LUBRICATION-. 

required no increased effort to produce motion, provided 
the same total pressure was exerted although the area 
of the surfaces in contact might be at variance. 

Recent investigations upon the friction of lubricated 
surfaces, made with the object of determining the laws 
governing the coefficient of friction with various grades 
of lubricants, have shown the contrary to be more like 
the true conditions than those previously stated. If 
the relationship of the ** resistance of friction as inde- 
pendent of the area of surfaces in contact, but depend- 
ent upon the pressure," were true, the temptation 
would be to reduce the work of friction and the abra- 
sion of the materials by an increase of the length and 
diameter of the journal. 

Practical demonstration, however, has proved the 
necessity of avoiding long journals ; while, with the 
friction of rotation, an increase in the diameter of the 
journal means a corresponding increase in the work 
of friction. These investigations have given results 
which will be found to accord quite closely with those 
obtained , from practice, and at the same time have 
given information of much value for guidance in the con- 
struction and management of lubricated surfaces where 
motion is present. They indicate, and quite conclu- 
sively, that friction is, when the rubbing surfaces are 
kept well separated by the lubricant, more dependent 
upon the nature and fluidity of the lubricant than upon 
the nature of the solids carrying the load. 

There seems to be a combined friction consisting of 
that inherent in the particles forming the lubricant and 
of the moving surface in contact with it. With con- 
stant pressure and temperature, it is dependent upon 



INTRODUCTION. 3 

the extent of surface in contact and varies directly 
with it. It is also influenced by the unit pressure, and 
varies directly with some ratio of the change in the 
load, but not in the same ratio as had been previously 
supposed. 

As the resistance of lubricated surfaces is made up 
of the resistance of the particles of the lubricant, it is 
evident that any influence that will change its fluidity 
will also affect the frictional resistance. 

Increase of temperature, increasing the fluidity, 
causes a decrease in the coefficient of friction ; while 
increase in unit pressure causes an increase in the dens- 
ity of the fluid, and, necessarily, an increase in the 
friction when motion is produced. 

The condition to be attained is that where the viscos- 
ity of the oil is such at the working temperature that 
it will be sufficient to keep the solids from contact 
under the pressure which must be sustained. 

The convincing point which should be kept in mind 
is the fact that frictional resistance and the abrasion of 
the surfaces is a representation of an expenditure of 
money, and of an amount greater than is generally 
supposed. The object of the following chapters will be, 
pure and simple, to reduce the conditions to a relation- 
ship the nature of which will assist towards reducing 
this expenditure, either directly or indirectly, to the 
lowest attainable figure. 

The problem will be treated in the following order : 

1st. The proportions and materials which are re- 
quired to meet the demands of the service. 

2d. The most economical way in which these may 
be applied. 



4 CAR LUBRICATION. 



CHAPTER IL 

THEORETICAL RELATIONS. 

The resistance of friction in car lubrication is that 
which is generally known as ^* sliding friction of rota- 
tion.'* It is similar to linear motion, but, as it is an 
arc of contact, it differs in the distribution of the load 
per unit of surface. 

When the bearing is first placed upon the journal 
the arc of contact is small, and it is only after wear has 
taken place that the whole arc included within the 
bearing is in contact with the journal. The amount of 
wear which is necessary to produce this condition is 
very small unless the radius of the bearing is made 
much larger than that of the journal, which must be 
classed as bad practice. 

It will be found that the greatest amount of the 
pressure is taken at the top of the journal, and de- 
creases in a determinable ratio, from that to the hori- 
zontal axis through the centre of the journal. The 
work of friction is then but a question of the space 
which is passed over against the frictional resistance 
which is offered to the rotation. The space in this 
case is a function of the circumference, and varies as 
the diameter of the journal. 

The law of the distribution of the pressure is as 
follows ; 



THEORETICAL RELATIONS. 5 

Let (see Fig. i) 
P = unit vertical pressure ; 
P^ = unit pressure in a radial direction ; 
R = radius of the journal ; 

Qo — angle made by the radius from a point with 
a vertical line through the centre of the journal ; 
/ = length of bearing ; 
L = total load carried. 
For any point, O^ 

P^=. P cos GO. 




Fig. I. 



The pressure upon a surface Rdoo is 
PJRdoo. 



6 CAR LUBRICATION, 

The summation of the pressure should be for an 
equal arc on each side of the vertical, or 

L = J^P.lRdoD^ 

and by inserting the value of P^, 

L ^^ I PIR cos GO doo. 

From this, the load carried by various arcs subtended 
can readily be obtained. The accompanying table 
will indicate the values for several values of go. It will 
also allow a comparison of the value of the pressure 
upon a 20° arc for higher values of oo. 





Average pres- 


Square inches 


Percentage car- 


Value of 


sure carried 


of surface 


ried by the 


m. 


per square 


when radius 


first 10® of 




inch. 


equal unity. 


the arc. 


10° ~ 


0.34729 


0.1745 


100.00 


20° 


0.68404 


0.3490 


50.78 


30° 


I. 00000 


0.5235 


34.73 


4° 


1.28558 


0.6980 


27.01 


50° 


1.53209 


0.8725 


22.67 



It is then evident that more of the pressure is taken 
by a small arc of the journal, and that the lower surface 
of the arc of contact figures as a less important part 
of the distributing surface for the lo^d. It would then 
appear that if the bearing had a surface contact of 3.5 
inches when the journal is four (4) inches in diameter, 
there would be very little cause of trouble arising from 
too high a unit pressure. It would also follow that the 
practice of boring out the bearing to a greater radius 
than the journal is open to no serious objection, pro- 
viding the difference in the radii is not made too great. 
When this is done a condition similar to that shown in 



THEORETICAL RELATIONS. 7 

Fig. 2 results. The sharp corners at A have a ten- 
dency to scrape the oil from the journal, and in that 
way give trouble. This effect will be more apparent 
further on. The condition shown in Fig. 2 will result 
in very poor lubrication, and Hkely produce a heated 
journal. In practice it is found that good results are 
obtained when the bearing radius is about one thirty- 
second (gi^) of an inch more than the radius of the 




Fig. 2. 



journal. This gives a safe working margin for a new 
bearing and journal. The difference in the radii be- 
comes greater when a new bearing is placed upon a 
worn journal. The detrimental effect which arises 
with a too large difference between the arcs of the two 
parts is overcome by lining the bearing with a soft 
metal of about one sixteenth (yig-) of an inch in thick- 
ness. 

Before stating the elements determining the work of 
friction, it is necessary to review in a general way the 
results of recent experiments which were made to de- 



8 CAR LUBRICATION, 

termine the laws governing the resistance to motion of 
bodies when separated by a lubricant. The reference 
is particularly to the experiments by Woodbury and 
Tower, the results from both of which, while made 
under different conditions, are corroborative. Those 
by Woodbury were made with low pressures, and the 
curves obtained from his results give a relationship of 
pressure and coefficient of friction, as shown in the 
diagram, marked as Fig. 3. They prove quite con- 
clusively that friction is not a direct ratio factor of the 
pressure as it is with solid surfaces ; but, on the con- 
trary, the laws seem to follow those of fluid friction 
more closely than those of solids. The result pro- 
duced by the motion of two solids under pressure is a 
more or less rapid abrasion of the metals in contact. 
With a lubricant interposed, the conditions are quite 
changed and follow more closely the resistance which 
the fluid would offer by its own friction. Whether or 
no this be a motion of the particles of the lubricant or 
of the solid upon the surface of the fluid matters not 
here. The important consideration is the extent of 
surface in contact which should enter as an element in 
the calculation of the work done. The friction should 
represent the resistance of the lubricant at the pres- 
sure carried, reduced to the resistance under these con- 
ditions for a unit surface. The resistance of friction 
would then consist of two elements : the coefficient of 
friction per unit of surface for the working pressure 
and temperature, and the number of units of surface in 
contact. Representing these hy f and a^ respectively, 
would give as the relationship of the total work of fric- 
tion 



THEORETICAL RELATIONS. 9 

W—f.a.p,27tRXn, 
where 

n = number of revolutions per unit of time ; 
p = pressure per square inch. 

With given pressure and temperature the minimum 
value of the function/".^ is determinable. 

First, the pressure and the temperature which it is 
necessary to meet will indicate the density of the lu- 
bricant which it is necessary to use to prevent the sur- 
faces coming in contact, and in the case of car lubrica- 
tion will vary w^ith the seasons of the year, causing a 
grading of the oils into those for summer, and lighter 
ones for winter service. Second, the value of a will 
depend upon the available space allowed for the journal. 
It will be seen further on that the results of the exper- 
iments indicate that the most economical conditions 
are obtained by increasing to within the practical lim- 
its the area and using a correspondingly lighter body 
oil for the lubricant. 

The value of a for the most economical results is 
where any further decrease in the resistance by the use 
of a more fluid oil is counteracted by the resistance 
resulting from the increased surface. More explicitly, 
the experimental results would indicate that by reduc- 
ing the unit pressure by increased area will allow the 
use of a lubricant of greater fluidity and a correspond- 
ingly less coefficient of friction. But in the case of a 
bearing upon a journal, it has been found that by in- 
creasing the arc of contact the additional surface ob- 
tained does not produce a proportionate decrease in the 
'pressure. The pressure which must be considered the 
ruling one, and influence the selection of the lubricant, 



lO CAR LUBRICATION-. 

IS included within a small arc at the centre of the bear- 
ing. Practically, an arc of contact of some magnitude 
is necessary for strength and stability, and to also give 
a fairly large area to accommodate for the abrasion 
which takes place. The increase beyond this arc is 
only economical so long as the increased surface de- 
creases the pressure carried by the centre arc to an 
extent that the lighter oil will, by the consequent re- 
duction in the coefificient of friction, overbalance the 
increased resistance produced by a greater area. As- 
suming c as the constant and necessary arc of contact, 
and GO as the desired angle, it is not economical to in- 
crease CD when the expression 

CD 

f-^ X 6.282 



IS greater than 



360 



/ -^ X 6.282. 



360 



f dind f^ indicate the coefficients of friction per unit of 
area for the lubricant which must be used to overcome 
the maximum pressure existing in the two cases which, 
in one sense, measures the fluidity of the lubricant. 

An increase of the length of the journal seems to 
be advantageous provided it is not carried beyond the 
limits placed upon it by practice. The diameter of the 
journal is dependent upon its length and the load to be 
carried. Taking the usual expression for a beam sup- 
ported at one end and uniformly loaded, we have 

TttR} 
^~ 8/ ' 



THEORETICAL RELATIONS, II 

where 7"= safe ultimate load for the metal, and the 
other symbols indicate the same as in previous formu- 
lae. 

For the deflection we have 



27tR^' 



where </ represents the deflection. All are indicated in 
pounds and inches. 

The formula for the variation of the diameter for 
changes in the length will be used again. 



12 CAR LUBRICATION. 



CHAPTER III. 

COEFFICIENT OF FRICTION. 

With the exception of the method of lubrication, 
there is no other element in connection with the sub- 
ject under consideration that has received more atten- 
tion than that of the coefficient of friction, and yet 
there is no other that is in as crude and indeterminable 
a state. As investigation progresses, the subject seems 
surrounded with more and more variables of a compli- 
cated nature which indicate the importance, if not ne- 
cessity, of the utmost refinement when the best results 
from lubrication are desired. 

The latest study of the subject has brought out some 
very interesting results, and has conclusively shown 
that it is now necessary to at least limit the old laws of 
friction to dry surfaces in contact, if not exclude them 
totally. The resistance of friction, when a medium is 
introduced between the so-called rubbing surfaces, fol- 
lows laws quite different and more intricate than those 
determined by Morin, which were to the effect that 
'' friction was independent of the surface in contact, 
but directly dependent upon the pressure keeping the 
surfaces together.'* 

Where friction is produced it is important to distin- 
guish between the two conditions to which the two sets 
of laws apply ; in one it is a solid against a solid, the 
particles of each interlapping and causing resistance by 



COEFFICIENT OF FRICTION. 13 

the efforts of the particles of one metal to tear away 
those of the other. Where lubrication is introduced it is 
intended that the two solids shall be separated by a film 
of the lubricant, generally a liquid. In this latter case 
the resistance assumes the nature of the laws of fluids, 
and consists of the friction of the particles of the lubri- 
cant and that of the solid against the fluid, forming a 
combined resistance, the percentage of each of the 
whole retardation depending upon the nature of the 
lubricant and the metal surfaces. As long as the metals 
are prevented by the lubricant from coming in contact, 
it is found the friction is dependent upon the fluidity of 
the lubricant, and varies with changes of this fluid con- 
dition, decreasing with a higher temperature and in- 
creasing with a less degree of heat. 

We will assume, first, that the lubricant in all cases 
prevents any contact of the metal surfaces. The con- 
dition then stands between the laws of solid friction on 
the one hand, — friction independent of the surfaces in 
contact, but dependent upon the total pressure, — and 
the laws of friction of liquids on the other, — that fric- 
tion is independent of the pressure per unit of surface, 
but is directly dependent upon the extent of surface 
and increases as the square of the velocity. From most 
recent investigation this intermediate condition has 
been found to be, when stated in a general way, that 
the coefficient of friction decreases with an increase 
of the pressure, although the total resistance rises 
directly but not proportionately with the higher unit 
pressures and increases with the velocity, although not 
as rapidly as its square. It is also found to be depen- 
dent upon the extent of surface in contact. An exact 



14 CAR LUBRICATION, 

relation between these varying conditions has not yet 
been obtained, evidently because they vary so materi- 
ally with any slight variation in the method used of 
lubricating the surfaces. As, for instance, when the 
oil bath is used the laws of lubricated surfaces, espe- 
cially as regards surface and pressure, follow those of 
liquid friction very closely ; while with less efficient 
means of lubricating the results give a more intermedi- 
ate result between solid and liquid friction. This mat- 
ter will be brought out more prominently in the chapter 
on the methods of lubrication. 

With the surfaces in good condition and the oil-bath 
method of supplying the oil, which may be considered 
as practically perfect lubrication, it was found that the 
mean resistance per square inch of surface with pres- 
sures varying from lOO to 310 pounds per square inch 
was as follows : 

Lubricant. Mean resistance in pounds. 

Sperm oil 0.484 

Rape oil 0.512 

Mineral oil 0.623 ! 

Lard oil 0.652 

Olive oil 0.654 

Mineral grease 1.048 

[Results obtained by Tower. — See Engineering for November 16, 
1883, and February 6, 1885.] 

The speed was 300 revolutions per minute, and jour- 
nal four inches diameter and six inches long, Avhile the 
temperature was maintained at 90° Fahrenheit. 

A constant temperature is essential for a proper 
comparison, as in one case with lard oil the coefificient 
of friction decreased to one third (^) its value at 60° 
by an increase to 120° Fahr., in the temperature of the 
lubricant. 



COEFFICIENT OF FRICTION, 1 5 

Probably the most accurate laboratory experiments 
made for the determination of the resistance of lubri- 
cating oils were those made by Woodbury for the North 
Eastern Cotton Manufacturers' Association as published 
in their Proceedings of April 28, 1880, and in the Pro 
ceedings of the American Society of Mechanical En- 
gineers as contained in volume VI. They were made 
with the object of appropriating the results to cotton 
and woollen machinery where low pressures are used, 
and to that extent are not well adapted to the lubrica- 
tion of car journals excepting as showing the action of 
lubricants under varying conditions of temperature 
and a limited range of pressure. They were presented 
about the same time as were the results of Mr. Tower's 
experiments, the latter, however, under heavier pres- 
sures, but both clearly showing the different conditions 
under which friction must be studied when solid sur- 
faces are lubricated by such bodies as the mineral and 
animal oils. It was found in the tests that uniform 
results could not be looked for unless constant tem- 
perature, velocity, pressure, area of surface in contact, 
and thickness of the film of the oil between the surfaces 
were maintained, the latter depending somewhat upon 
the method of lubrication, indicating at once that the 
resistance of friction was dependent upon and changed 
with a variation in any of the above conditions. The 
metallic surfaces were cast iron and bronze, the latter 
composed of copper 32, tin 2, lead 2, and zince I. In 
one case all conditions were kept constant excepting 
that of pressure, the diagram represented as Fig. 3 
indicating a decrease in the coef^cient of friction, but 
an increase of total resistance. Similar tests were made, 



i6 



CAR LUBRICATION. 



keeping the pressure constant and varying the tem- 
perature, which gave the effect of the variation of the 
temperature upon the coefificient of friction. 

The two diagrams, Figs. 3 and 4, indicate by the 
two curves the variation which takes place in the coefifi- 
cient of friction under the varying conditions. 

In Fig. 4 it will be noticed that the variation in the 
coefificient of friction due to changes in temperature 
follows closely the laws of the straight line indicating 
a proportionate decrease with the increase in tempera- 




120 



«110 

t 

i'lOO 



90 



& 80 



70 



\ 


\ 












\ 


\ 


Te 
of 


aperat 
Frictio 


andC 
i,Taryi) 


oefficic 


at 




\^ 


Pr 

\ 


ssure, 
poui 


;oasUii 
dsper 


t=2a 
iquare 


nd5 

nch 




\ 


\ 












\ 


\ 


\ 












\ 


\ 












\ 


\ 


V 










\ 




\ 







.10 .20 .30 .40 .50 

Coef. of Friction. 

FjG. 3. 



.10 .20 .30 .40 .50 
Coet of Friction. 



Fig. 4. 



ture ; the angle of the hne with the abscissae depending 
upon the pressure per square inch. 

Combining these two diagrams gives a curve for the 
coefificient of friction as shown in Fig. 5, where the two 
variables, pressure and temperature, are considered, and 
it is this relationship w^hich most concerns the lubrica- 
tion of surfaces such as car journals. In that practice, 
the temperature is subject to changes occurring from 
changes of seasons and weather, while the pressure 
carried per square inch is dependent upon how long 



COEFFICIENT OF FRICriON. 



17 



the bearing has been subjected to wear and attrition, 
the unit pressure decreasing with increase of service. 
While the results obtained by Woodbury are the most 
accurate that have been published and probably ever 
made, both as regards design of apparatus as well as its 
manipulation, there still lacks sufficient uniformity for 
the derivation of a definite law as to the variation of 
friction with changes in temperature and pressure. 





> 


V 
















\ 


Tei 
Co 


iperatA 
efficiei 


re and 
tofFr 


Pressu 
ictioD, 


re varying. 
constant 


|lGu 

|90 

^ 80 

•70 




\ 


\ 








= 0.25 






\ 


k 














\ 
















\ 
















\ 




C 




J»re33 


urepei 


squon 


dnch. 


J 





Fig. 5. 
Note. — The coefficient of friction in the three cases is represented 
in actual pounds resistance. 

For instance, the decrease in the coefficient of friction 
as given in table below for pressures of from one (i) to 
five (5) pounds per square inch is: 



Pressure 

per square 

inch. 

Pounds. 


Coefficient of 
Friction. 


Decrease in 

Coefficient of 

Friction. 


Difference in 

the amount of 

decrease. 


I 
2 
3 

4 
5 


0.3818 
0.2686 
O.2171 
0.1849 
0.1743 


0.0000 
O.II32 
0.0515 
0.0322 
O.OT06 


0.0000 
0.0000 
0.0617 
0.0193 
0.0216 



The decrease in the coefficient of friction from an in- 
crease of pressure of one (i) to two (2) pounds was 



1 8 CAR LUBRICATION'. 

0.0617 more than that from two (2) to three (3) pounds, 
while the increase from three (3) to four (4) pounds was 
0.0193 and nearly the same as took place when the 
pressure was increased from four (4) to five (5) pounds. 

The above is cited more to prevent a deduction of 
too wide a nature rather than to deter from the grati- 
tude which the engineering profession must feel for 
the derivation of the general law of the variation of 
friction with lubricated surfaces when the temperature 
and pressure are varied. The care which it was neces- 
sary for Mr. Woodbury to exercise to obtain these 
results can be appreciated when it was found essential 
to run the apparatus, using gasoline or its equivalent, 
to clean an oil from the surfaces after testing. It re- 
quired a travel of one surface over the other equivalent 
to about forty (40) miles before it was advisable to 
commence the trial of the succeeding oil, and even then 
indications could be noticed in the test following of 
the properties of the oil previously tried. This is con- 
sidered further evidence that the friction of lubricated 
surfaces is made up of the friction of the fluid and 
tends to prove that the lubricant embeds itself into 
the surface of the metal, producing a fluid resistance 
rather than a resistance due to the rubbing of the sur- 
face of the metal upon the surface of the lubricant. 
This effect will be taken up again in the chapter on 
Bearing Metals. 

The variation in the coefficient of friction with 
changes of temperature is readily carried to an ex- 
treme, as it has been found that while the resistance 
decreases as the temperature is raised, there is a point, 
depending upon the unit pressure and viscosity of the 



COEFFICIENT OF FRICTION, IQ 

lubricant, where the coefficient starts to increase very 
rapidly with increase of temperature. The same holds 
true with a variation in the pressure ; and while the laws 
of changes are true as stated, in a general way, they 
depend and are limited by the viscosity of the lubri- 
cant used, and also the pressure which it is necessary 
to carry. The rapid increase, when the limits of tem- 
perature and pressure are exceeded, is due to the solids 
coming in contact and causing increased friction by the 
abrasion of the surfaces, reducing the condition from 
friction of fluids to that of solids. 

An attempt has been made to prove a positive rela- 
tionship between the viscosity of an oil and its coeffi- 
cient of friction ; and while they are, no doubt, more 
or less dependent, there are hardly sufficient accurate 
data at hand to make the relationship a positive one and 
free from the possibility, if not probability, of a more 
or less dependence of friction upon a property which 
might be termed unctuousness in addition to that of 
viscosity. It appears, and there seems sufficient in- 
formation at hand to anticipate it, that a relationship 
of a positive and determinable nature between the three 
elements, coefficient of friction, viscosity and unction, 
is obtainable. 

The results of the experiments made by Mr. Tower, 
as presented before the British Institute of Mechanical 
Engineers, are of such a nature that they can readily be 
converted into practice with a resulting profitable ap- 
plication. They go to corroborate, to a close degree, 
the results of Mr. Woodbury, although they have the 
advantage of having been made with higher pressures. 
It should be remembered that with high pressures, 



-30 CAR LUBRICATION. 

such as those obtained before seizure takes place, the 
film of oil separating the bearing and journal has been 
found to be as small as 0.05 of an inch, which would 
indicate the result that may be expected with a bear- 
ing where the irregularities or projections on the sur- 
face of the journal or bearing are greater than the thick 
ness of the film of oil used to separate them, producing 
when in motion a rapid and detrimental abrasion of the 
metals with a marked increase in the friction. It 
would not be safe to allow particles to project from the 
surface more than 0.05 of an inch — unless, of course, 
the prevailing area is of this height. The other extreme, 
of having the surfaces too highly polished, must not be 
selected, as it has been found that a moderately rough 
machined surface will carry something like seven (7) 
times more pressure before seizing than can be obtained 
from highly polished surfaces. The proper condition 
would seem to be about that produced by a boring tool, 
except with the soft metals, which from their nature 
are incapable of taking a high polish. 

For the purpose of comparison, let us consider 
briefly some of the results obtained by Mr. Tower where 
the journal was lubricated by the oil-bath method and 
the surfaces were in good condition. Assuming a 
loaded car of total weight of 80,000 pounds would give 
10,000 pounds per journal. At a pressure of 300 
pounds per square inch this would require a bearing 
area of 33.33 square inches to carry the load. With 
the resistance given for mineral oil of 0.623 pounds per 
square inch and a journal of 4 inches and a wheel 33 
inches in diameter, a tractive resistance of 2.52 pounds 
per journal or of 0.504 pounds per ton would be re- 



COEFFICIENT OF FRICTION, 21 

quired after motion had been produced. With the 
latest dynamometer readings the resistance of journal 
friction for loaded cars will probably reach as low a 
figure as 2 pounds per ton on level tangent when run- 
ning at a speed of 15 miles per hour. Retracing, this 
figure gives a journal resistance of 82.5 pounds and as 
high a figure as 2.48 pounds per square inch of bearing 
contact. It will be seen how low an efficiency is ob- 
tained in practice; but it should be remembered that the 
above laboratory tests were with the oil-bath method of 
lubrication, which has proven, when so tried, to be far 
superior to any other method that is at present known 
for lubricating surfaces. In most cases it has been 
found that the resistance of friction is a direct propor- 
tionate function of the area of surfaces in contact; twice 
the bearing surface, all other conditions remaining 
the same, will give, approximately, twice the resistance 
from friction. 

The information as presented by the theoretical tests 
of oils is of much importance in the selection of the ones 
best suited for the conditions of the particular service. 
The conditions here met are not, however, such as will 
allow the delicately calculated conditions of a constant 
relationship of bearing surface, lubrication, temperature, 
and pressure, but require a large factor to be used to 
cover the variation which takes place in the service. 
For instance, when starting with a new bearing, the 
surface in contact is much less than when it has worn 
down to a point where the whole arc of contact has 
been obtained. This is one of the conditions which 
must be met, for with the irregularities of the parts 
accompanying the distribution of the load it is found, 



22 CAR LUBRICATION, 

excepting with the so-called soft-bearing metals, that 
heating will almost invariably result if the bearing is 
fitted to the journal throughout the whole arc which it 
is capable of including. There seems to be a binding 
action on the journal. If the bearing is so fitted 
as to allow a small amount of motion, the wear will 
take place in a manner consistent with the alignment 
of the journal-box. The variation in the unit pressure 
is not, however, as wide as would at first be supposed, 
as will be seen on reference to Chapter II, where the 
variation in unit pressure due to changes in arc of 
contact are given. The viscosity of the oil selected 
should then be such that it would keep the surfaces 
apart under the conditions of minimum arc of contact, 
and at the highest temperature that will be met. This 
temperature is not dependent altogether upon that of 
the atmosphere, but, on the contrary, will vary much 
with the nature of the service. For instance, with 
long, continuous fast runs the temperature of the jour- 
nal will be considerably above that of the atmosphere. 
With this service, the heat arising from the work of 
friction will be such as to raise the temperature of the 
journal and bearing before a constant condition is 
reached. The conductivity and radiation of the heat 
through and from the surfaces is not sufficiently rapid 
to accommodate for all the heat generated. It will not 
be found uncommon for journals in severe service to 
reach a temperature of a hundred and fifteen (115) de- 
grees Fahr. with the atmosphere only 50 to 60 degrees. 
This is to the advantage of the lubrication, provided an 
oil has been selected with sufficient body to meet the 
conditions. If such has not been provided, the parts 



COEFFICIENT OF FRICTION, 23 

are reduced to such a sensitive state that the slightest 
cutting from the entrance of foreign matter between 
the bearing surfaces is apt to result in an overheated 
journal, or what is generally known as a hot box. The 
maximum pressure per square inch that must be sus- 
tained without seizure at the highest temperature that 
will be reached will determine the grade of the oil which 
it will be necessary to use. The resistance is a mini- 
mum when the product of the coefificient of friction 
into the area in contact is a minimum. When the 
limitations of the case require the use of high unit 
pressures, correspondingly heavier oils must be used to 
prevent the bearing seizing the journal ; but that oil, 
all other variables remaining the same, which will give 
the lowest coefficient of friction and prevent the sur- 
faces coming in contact is the one to be used. 

The work done is dependent upon the circumference 
of the journal, so that any change in the diameter of 
the journal affects correspondingly the work of fric- 
tion. The diameter of the journal varies as 3.175 V l^. 
The work of friction is dependent upon the coefficient 
of friction per unit of surface, the area in contact and 
the distance travelled ; or, depends upon 

W= lAy^nafn V~T^. 

The variation in the diameter is that necessary to 
maintain strength for the changes in the length. Re- 
ferring to the table on page 14, we are enabled to infer 
as to what are the intrinsic values of the heavy and 
light oils upon the resistance due to the work of fric- 
tion. For instance, Tower found that with rape-seed 



24 CAR LUBRICATIOA\ 

oil the pressure which it would resist up to the point 
of seizure was ,573 pounds per square inch, and with 
mineral grease a pressure of 625 pounds per square 
inch. To make a comparison between sperm oil, which 
is of still Hghter body, and mineral oil, we would have, 
assuming a proportionate power of resisting pressure, 
of 541 pounds pressure as the capacity of the sperm 
oil. Taking this oil, and with a bearing surface of i|- 
by 8 inches, we find it would require for mineral oil 

li X 8 625 • u f r . 

zzi or 10.4 square mches of surface to sus- 

X 540 

tain the load. The corresponding length would be 6.9 

against 8 inches with sperm. The expressions for the 

work of friction in the two cases would be 

and their ratio 

f =0.484, a = 12, /j =8; 

f = 0.623, a' = 10.4, // = 6.9 ; 

112.73 
r = = 0.91 1. 

It is very evident from these figures that the heavy 
oils, even with the decrease of bearing surface which 
they allow, are not as economical as the lighter ones, 
so that the work of friction is least where the limita- 
tions are such that they will allow an increase in the 
length of journal, resulting in an increase of the bear- 
ing surface, when an oil of light body may be used. 



COEFFICIENT OF FRICTION. 2$ 

This conclusion has, of course, its practical limits, as 
well as modification by results of the resistance value 
of oils from more thorough experimental results. By 
again referring to the table, it will be found that the 
values of the mean resistances per square inch are for 
pressures varying from lOO to 310, while the resistances 
for several values between these limits would be of 
invaluable assistance where results between these limits 
are desired. 



26 CAR LUBRICATION. 



CHAPTER IV. 

BEARING METALS. 

The questions of oil and bearing metal, in their re- 
lation and application to car lubrication, are capable of 
almost indefinite treatment, so much so that it has now 
become the work of a specialist to properly follow each 
and advise as to their efficiency. The adulteration of 
oils made them a subject of suspicion and necessitated 
rigid specifications and inspection to eliminate the 
probability of such deterioration. This having been 
successfully accomplished, through proper specification 
and inspection, the next point is the selection of the oil 
best suited for the journals to be lubricated. This re- 
quires the consideration of properties in addition to 
that of their coefficient of friction. These are such as 
the rate of evaporation at the working temperature, 
the tendency of spontaneous combustion from the 
evaporation, the decomposition of the oil by the at- 
mosphere, and, still further, that of the chemical action 
of the acid, — which animal and vegetable oils contain 
to a greater or less extent, — upon the metals used for 
the bearing. 

For instance, an oil whose exposed surface gave an 
evaporation of 20 per cent would be far inferior to one 
which gave but 10 per cent evaporation at the same 
temperature and in the same time. It is also objec- 



BEARING METALS. 2/ 

tionable on the ground that the oil giving the higher 
evaporation would also be more liable to give trouble 
from combustion arising from the rapidly vaporized oil. 
Care must be taken not to conflict the flashing point 
with the rate of evaporation, as they are not in any way 
relevant, for it has been found * that, in one case, two 
oils having the same flashing point gave the rate of 
evaporation of 9.4 and 24.6 per cent respectively. When 
determining the percentage of evaporation of oils for 
comparison, the surface, time, and temperature should 
be the same in all cases, as otherwise it would not be 
a true comparison. The mineral oils have a low evap- 
oration, and when mixed with those of an animal and 
vegetable nature prevent, to a large extent, the spon- 
taneous combustion which is otherwise apt to arise and 
give trouble when the latter are used alone. The chemi- 
cal effect arising from exposure to the atmosphere is of 
much importance in its influence upon the lubricating 
value. This action, with the fine particles of dust or for- 
eign matter which enter through the front and back of 
the box, reduces the top of the waste to a pasty condi- 
tion which materially depreciates it as a lubricant. It 
should be remembered that the result obtained from 
the use of mineral with the animal oils is dependent 
upon their relative proportions and the temperature to 
which the mixture is subjected. The use of the petro- 
leum products has a remarkable effect toward reduc- 
ing the tendency to inflame so common with the animal 
and vegetable oils when used alone. The relative value 

* See Prof. Ordway, in Proceedings of Semi-annual Meeting of 
N. E. Cotton Manufacturers' Association held in Boston, Oct. 
30, 1878. 



28 CAR LUBRICATION, 

of oil from the standard of percentage of evaporation 
and inflammability is unknown ; in fact, it is as yet an 
undeveloped field, but represents properties which must 
sooner or later enter as factors in the efficiency of an oil 
for lubricating purposes. The importance of these will 
be appreciated from the results which Ordway found, 
where with one oil the evaporation in twelve hours at 
a temperature of 140 degrees (Fahr.) was 24.6 per 
cent. 

As well, too, should the question of the chemical effect 
of the acids in the oil be taken into consideration. For 
these two reasons the mineral oils are coming into 
general use for car-lubricating purposes, while they also 
give, from their lubricating qualities, as low a coefficient 
of friction as any of the animal or vegetable oils. They 
can be obtained of almost any desired gravity and fire 
test, and, when clean, are particularly well adapted to 
the service in question. 

The brass-foundry practice of to-day is still so much 
dependent upon empirical laws that it is impossible 
to form any definite or concise conclusion as to the 
exact nature of the alloy, all things considered, which 
gives the best results for car bearings. So much de- 
pends upon the foundry treatment that a chemical 
analysis is of very little value from which to draw any 
definite conclusions as to the nature of the service 
which a known mixture of metals will give. The same 
ingredients differently treated will give alloys of marked 
variation in their physical properties, and until the 
foundry working can be reduced to a more, accurate 
science we must be subjected to the so-called kinks 
which have in some cases produced metals of remark- 



BEARING MKTALS, 29 

ably good wearing qualities. This is illustrated in 
phosphor bronze, where the metal as produced contains 
about 0.75 per cent of phosphorus, while about one (i) 
per cent was used during the treatment. 

The effect of the phosphorus is to produce a more 
solid casting by reducing the amount of oxidation 
which takes place during the mixing of the metals. 

The metals used for bearings may be classed about 
as follows : phosphor bronze, brass, and the so-called 
white metals, the latter containing a large percentage 
of lead, zinc, tin, or antimony, with but little or no 
copper. 

Each has a wide range of hardness, but from all that 
can now be gathered the white metals give excellent 
service and wear less than the harder alloys. In 1883 
the writer had an excellent opportunity to compare, in 
a general way, the service of a hard bearing with one 
composed of antimony and lead — the latter material was 
run into an iron shell. The two roads were located in 
the same country and had the same destination and, 
as near as could be, the same service. The bronze re- 
quired, as an average, a consumption of oil of 0.945 
pound, and the white metal an oil consumption of 
0.3075 pound, each, per car per 100 miles. Where the 
bronze was used it was necessary to resort to lard oil, 
making the cost per car per 100 miles in the two cases 
6.3 and 0.88 cents respectively. 

The white alloy was remarkably free from heating, 
while with the bronze bearings hot journals were giv- 
ing continual annoyance. 

As regards the wear of the soft and hard metals, the 
experience with bearings lined with lead alone indicates 



30 CAR LUBRICATION. 

the remarkably long service which can be obtained 
from even a lining but -^-^ of an inch thick. Experi- 
ments as given in the Railroad Gazette for March 5, 
1886, are much in favor of the white metals. 

There is some difference of opinion as to the resist- 
ance of friction with the two alloys, as well as their 
effect upon axle wear, neither of which points has, 
as far as known, been proven to a satisfactory con- 
clusion, and the field of the determination of the 
best wearing metal is open to valuable research. As 
regards axle wear, however, it will be seen, by reference 
to the chapter on the cost of lubrication, that bearing 
metal and axle wear are almost equal in value for the 
loss resulting from abrasion per 1000 miles. With soft 
and hard metals moving together the result is always a 
more rapid abrasion of the harder one. This is where 
the surfaces are separated by a grinding material ; but 
when properly lubricated the condition is quite differ- 
ent, as then the separating material is fluid and slow in 
its wearing action ; and, from the experience of those 
who have the white metal in general use, the wear is 
not increased by the particles of dust which its op- 
ponents claim become imbedded in the bearing, and 
in that way exercising an additional grinding action 
upon the journal and increasing the wear over that 
produced by the harder metals. 

While there seems no reason to expect a more rapid 
wear of the journal from the softer metals, yet it is a 
subject seriously affecting the cost of lubrication and 
one upon which there lacks sufficient information to 
warrant the positive assertion that the softer metals are 
superior to the harder ones for bearings. Experience 



BEARING METALS. 3 1 

SO far, however, seems to be in favor of the white 
metals. 

There has been a tendency to attribute the metal 
contained in an oil that had been in service to the 
wearing of the bearing, but the experiments of Volney 
will show the relative action of different oils upon the 
decomposition of brass. The figures also represent the 
values of the oils in this respect, and, together with the 
oxidation which results from exposure to the atmos- 
phere, would indicate their influence towards producing 
the pasty condition of the waste. The dissolving power 
should act in its relative importance for the selection 
of the oil that is to be used. It would also indicate 
that the percentage of the bearing metal found in the 
oil of a journal-box is not all due to abrasion. 

From the fact that the mineral oils have less action 
upon the bearing metal and are less influenced by the 
atmosphere the comparison would still further corrob- 
orate the excellent results which can be obtained by 
the mineral oils when such are used for car lubrication. 
They maintain a more uniform condition than either 
of those of vegetable or animal origin. 

Name of Oil. Relative Dissolving Power. 

Menhaden oil 0.511 

Neatsfoot " 0.505 

Olive oil 0.504 

Crude cotton-seed oil 0.348 

Lard oil 0.131 

Crude petroleum from Scio 0.000 



3^ CAR LUBRICATION. 



CHAPTER V. 

METHODS OF LUBRICATION. 

To persons unacquainted with the details of car 
lubrication there must appear a degree of scepticism far 
beyond that which seems reasonable. The devices that 
have been arranged and the so-called inventions that 
have been patented to lubricate car journals are innu- 
merable, and yet there is not one at present in use that 
can be said to be in such a stage of developements as 
to be superior to the method of using cotton or woollen 
waste when this is properly arranged and manipulated. 

The writer has had experience with numerous de- 
vices, most of which were arranged to lubricate from 
the under side of the journal. The nature of such 
devices was various ; some were made up of a revolving 
cylinder in contact with the under surface of the jour- 
nal, while the lubricating mechanism ran in oil. The 
roller, when such is used, receives its motion from the 
journal in which it is kept in contact by a spring or 
some similar arrangement. Devices of this general na- 
ture have been made in numerous quantities, all differ- 
ing only in some minor detail. None of them have 
been known to produce satisfactory results. Mechani- 
cal methods in the nature of pads kept in contact with 
the journal by spring have been tried, but from a thor- 
ough trial the results seem to indicate that the elasticity 



METHODS OF LUBRICATION. 33 

of the waste commonly used is superior to the 
mechanical devices, not only in the quality of the 
lubrication, but also in the mileage rendered. One 
case is known where an attempt was made to lubri- 
cate by feeding oil through the top of the bearing, 
and by waste at the bottom of the journal, similar to 
boxes used on foreign roads; and although the trial 
was of short duration, no apparent advantage over the 
generally accepted m.ethod were noticeable. Devices 
have also been attached to the front of the journal for 
lifting the oil to the bearing, some of which have proved 
fairly satisfactory. In fact, the possible methods of 
lubricating journals is innumerable ; but with the me- 
chanical devices, the objection which can be predicted 
to a fair certainty is the resulting failure from even a 
small percentage of breakage, while even their intro- 
duction to an extent to test this conclusion is a result 
as yet far distant, as no satisfactory method of this na- 
ture for lubricating a journal in an efficient manner is 
now more than in the experimental stage. We may 
except the so-called roller bearings, which have been 
tried with more or less satisfaction in an experimental 
way. The theoretical advantage arising by resolving 
the friction from that of sliding to that of rolling would 
appear to be a large gain; and yet from the experiments 
of Wellington (see Proceedings of American Society of 
Civil Engineers) it would appear this advantage is indi- 
cated only during starting, but is not so large a per- 
centage gain after the velocity is increased. Roller 
bearings have been known to run successfully for loo,- 
OOO miles, but it is not known that they have been sub- 
jected, by a more general introduction, to an extensive 



34 



CAR LUBRICATION. 



trial to determine their mechanical efficiency, such as 
wear and tear and comparison with bearing metal. 

The results of Tower's experiments, previously re- 
ferred to, give a close idea as to what is to be expected 
of the different methods of lubrication. It was found 
with three (3) methods of lubricating journals, feeding 
the oil from below and from above the journal, that 
the following ratios of their efficiencies may be ex- 
pected : 



Method. 


Actual Load. 

Poundsper sq. 

inch. 


Coefficient 
of Friction. 


Comparative 
Friction. 


Oil Bath 


262 
252 
272 


0.00139 
0.00980 
0.00900 


I 00 


Siphon Lubricator. 


7.06 
6.48 


Pad under journal 





The siphon lubricator was placed on the top of the 
bearing. The tests were under the same conditions. 
Rape-seed oil used. Journal, 4 inches diameter, run- 
ning at a speed of 150 revolutions per minute. Tem- 
perature 100 degrees (Fahr.). 

There can be no question, then, as to their relative 
efficiencies. The oil-bath method has had numerous 
trials upon car journals, but has always proved a fail- 
ure from the difficulty of obtaining ameclianical means 
that would retain a tight joint at the back of the box 
unless it be made of such a complicated nature as to 
outweigh, on account of repairs, the advantages accru- 
ing from the method. The siphon method has objec- 
tions on account of the high resistance offered, the 
cause for which will appear further on. It can safely 
be concluded that the use of a pad under the journal 
gives a higher resistance than would be obtained with 
what is known as waste, due to the closer texture 



METHODS OF LUBRICATION, 35 

which its name implies. This gives it less power to 
absorb the oil, the importance of which is evident from 
the high efficiency obtained with the oil-bath method 
of lubrication. Two surfaces that fit tightly when 
dry can be made to move easily on one another by 
interposing a lubricant. It would seem, with the 
resistance arising from the tight fit when dry, that 
the introduction of additional material between their 
surfaces would offer still more resistance to their 
motion. The application is so common that the 
reason why it should be so is generally lost sight 
of. With this exceedingly thin layer of oil, whether 
in the nature of globules which have penetrated the 
pores of the metal, or a continuous layer of the 
lubricant between the surfaces, the result indicates the 
strength of the wedging action influencing the intro- 
ducing of a lubricant between the metals in contact. 
This is quite the same action as when lubricating by 
means of an absorbent material saturated with the 
lubricant which is in contact with the lower side of 
the journal, unless the bearing grips the journal and 
scrapes the oil from the surface, in which case the ob- 
ject is defeated. With rolling friction, from the nature 
of the distribution of the load, it will be noticed by 
referring to Chapter I that the radial pressure upon 
the journal increases from zero, when the bearing in 
eludes a semicircle, to a maximum which is on a ver- 
tical line through the centre of the journal ; that is to 
say, the nature of the distribution is such as to make 
the action the same as that of a wedge even when 
the bearing is in contact throughout the whole of its 
arc. It is an increase from a small to a large pressure 



3^ CAR LUBRICATION. 

per unit of surface. The results of Tower are prac- 
tical demonstrations of this effect. During the prog- 
ress of the experiments with the oil-bath method of 
lubrication he had occasion to remove the bearing. It 
was then decided to insert a lubricator in the top of 
the bearing, for which a J-inch hole was drilled* After 
re-starting the experiments and before the cups were in- 
serted in the top, oil was observed to rise in the hole 
which had been drilled, and was noticed to exude at con- 
siderable pressure, which, when indicated on the gauge 
attached to the top of the bearing, was found to be 
more than 200 pounds per square inch, while the 
average pressure (vertical) upon the bearing was 100 
pounds per square inch. It was further found, when 
a groove was cut the whole length of the bearing and 
a lubricator attached to feed oil to this groove, that 
even with a pressure of seven (7) inches head of oil, it 
would not feed to the bearing, but, on the contrary, it 
appeared to be the means of escape for the film of 
oil between the bearing and the journal. When the 
cup lubricator was the only feeder, the bearing would 
not run cool with the pressure as low as 100 pounds 
per square inch. In this case, care was taken to cham- 
fer the edges of the groove to prevent any scraping 
action. As the point of application of the lubricant 
was moved from a vertical towards a horizontal direc- 
tion, the friction decreased and the bearing was found 
capable of carrying greater pressure before seizure. The 
experiments by Tower to determine the pressures at 
different parts of the bearing are so indicative of the 
wedging action which takes place that they are referred 
to somewhat in detail. The bearing was divided into 



METHODS OF LUBRICATION 



37 



three (3) vertical planes lengthwise of the bearing, and 
each half into three (3) planes at right angles to the 
first ones. 




Fig. 5. 

The lubricator was placed on the intersection of the 
planes passing through No. o, No. I, and No. 2, and 
the same pressures assumed for No. i A and No. 2 A 
— rather an unfortunate assumption, especially as the 
means of distribution may have had an effect upon the 
pressure at the points on the rear half of the bearing. 
The results were as follows : 



Longitudinal Planes. 


On. 


Centre. 


Off. 


Transverse Plane No. 0. . . . 

'♦ No. I 

'' No. 2.... 


370 
355 
310 


625 
615 
565 


500 
485 
430 



The figures represent in pounds the pressures per 
square inch. The bearing had a total load of 8008 
pounds, the journal running at a speed of 150 revolu- 
tions per minute. Temperature constant at 90° (Fahr.). 
Journal 4X6 inches. 

The maximum pressure is at the centre, as was to be 
expected ; but the increase on the off side of the bearing 
would go to indicate that the wedging action is so dom- 



38 CAR LUBRICATION, 

inant as to actually skew the bearing on the journal, 
and would do so where there is clearance between it 
and the sides of the box to allow of any such motion. 
That such results are shown by experiments which 
contradict the more or less satisfactory practical use 
obtained when surfaces are lubricated from the top 
can be attributed only to the effect of the end play of 
the bearing on the journal, and to the change in posi- 
tion when the bearing and journal are not as closely 
fitted as was the case with the apparatus which Mr. 
Tower used and which was probably necessary for the 
nature of the tests which he made. It then becomes 
apparent that the method of oiling from the under or 
exposed part of the journal is by no means the most in- 
efficient one, but, on the other hand, seems to be the 
best way of introducing the lubricant. Inasmuch as 
the oil-bath method has been found impracticable, the 
result obtained by it is a favorable indication to 
the now generally accepted plan of using waste satu- 
rated with oil. To obtain the very best results in 
this way, however, it is necessary to observe a num- 
ber of the details of the method. For instance, when 
using new waste it is important, in fact necessary, 
to thoroughly saturate it before placing it in service, 
the importance of which is probably sufficiently indi- 
cated from the following experiment. It was the prac- 
tice to oil journal-boxes of passenger- equipment cars 
at the end of each of the sub-divisions of a through 
line with the object of preventing the occurrence of 
heated journals and assuring the condi ;ion of good lu 
brication. To test the necessity of this method a car 
was selected the journal-boxes of whicli were carefully 
cleaned and repacked with new waste which had, for 



METHODS OF LUBRICATION, 39 

some few hours before, been thoroughly soaked in oil. 
For some two hundred miles of the run after re- 
packing, the journals were very warm and had almost 
reached the point where scaling of the surface of the bear- 
ing takes place. No oil was placed in the boxes, how- 
ever, especially as it was found that the journals seemed 
to become cooler as the distance run was increased. 
The car was taken some four hundred and fifty (450) 
miles, when the journals were very cool and reached 
their destination in good condition. The car was re- 
turned to the starting point, and it afterwards made a 
second round trip, covering in all eighteen hundred 
(1800) miles with one oiling, and yet at the start it 
seemed as though the car would not succeed in cover- 
ing more than one hundred (100) miles before trouble 
would arise. The warm condition of the journal and 
surrounding parts increased the fluidity of the oil and 
apparently enabled the waste to more easily absorb it 
and exercise its capillarity. That the waste at the end 
of the second round trip was still in good condition 
partly indicates what can be accomplished by system- 
atic attention, although the trial does not indicate a 
successful but rather a dangerous way of saturating the 
waste. It is cited to emphasize the importance of hav- 
ing the waste well saturated before placing it in boxes. 
In a short paper read by the writer (see Proceedings of 
Engineers' Club of Philadelphia, fall of 1886) there is 
given the result of a crude experiment made with the 
object of roughly determining the absorptive powers 
of fibrous and woollen waste. A small quantity of dry 
woollen waste was taken, one end of which was placed 
in a large cup half filled with oil, and the other end, 



40 CAR LUBRICATION, 

after passing over the top of the cup, was allowed to 
pass down the outside and rest upon a table. After 
standing some twenty-four (24) hours, the waste was 
oily to the touch and a small oil-spot was found upon 
the table. The waste was allowed to remain in this 
condition for some two (2) or three (3) days, but 
seemed to absorb but little if any more of the oil, in- 
dicating the almost inconsiderable effect of capillarity 
in comparison with what is already known as its ab- 
sorptive power. When the best results are desired 
from this method of lubrication, the necessity of 
thoroughly saturating the waste, that is, covering it 
with oil for some days before using, becomes appa- 
rent. The object should be to produce with waste, 
as near as can be obtained without incurring the 
loss resulting from splashing, the condition known as 
the oil-bath method of lubrication. To obtain such a 
result we cannot depend much upon the capillarity of 
the material. The condition to give this end, it seems, 
should be to obtain a state of saturation such that the 
journal is continually replenished with oil as it revolves. 
The degree of saturation will decrease from that at the 
bottom of the box to the top of the waste. The top 
of the waste should contain an amount of oil just be- 
low the state where it will run from the back or front 
of the box, hence the advisability of having these points 
oil-tight ; they not only reduce the loss of oil, but also 
render a lower resistance from friction. The small 
amount of dependence which can be placed upon capil- 
larity can also be tested and proved by an examination 
of the waste of a journal-box which has been in service 
some months. That at the front will be found to be 



METHODS OF LUBRICATION, 4 1 

much better saturated with oil than the waste at the 
back of the box. For this reason it is thought the oil 
should be introduced into the box at some point about 
midway of the journal, which can readily be done by 
small openings in the front and leading back by cored 
passages to any point where it is desired to bring the 
oil in contact with the waste. 



42 CAR LUBRICATION. 



CHAPTER VI. 

JOURNAL-BOX CONSTRUCTION. 

JOURNAL-BOXES have been made in numerous ways, 
in some cases all the attention having been given to 
the exclusion of dust at the rear of the box, as the most 
important constructional feature, while with others, to 
facilitate oiling and at the same time make a dust- 
and oil-tight joint, the study has been given to the 
opening at the front of the box. 

The distribution of the load, however, seems to have 
received less attention than either of the two preced- 
ing. It is unnecessary to give a historical review here 
of the numerous devices which have been tried to 
make the box dust- and oil-tight; but suffice it to say 
that efficient means to accomplish these results, espe- 
cially for the back of the box, are too much overlooked. 
A good dust-guard seldom proves a bad investment ; 
it should, however, be simple in design and of a ma- 
terial that will not be affected by the oil used for the 
lubrication. It should also accommodate itself to the 
wear of the bearing. 

The method of distributing the weight upon the 
bearing is an interesting analysis, and, if not carefully 
followed, will produce results from which considerable 
trouble may arise. From the conditions of the case it 
will be well understood by those at all familiar with 



JOURNAL-BOX CONSTRUCTION, 



45 



the design and nature of the mechanical appHances 
used for carrying the weights of cars that mechanical 
accuracy in the parts cannot be obtained. Especial 
reference is made to the condition of the seat in the 
top of the box and the top of the bearing, both of 
which are rough castings, and, however clean and 
accurate these may be in the rough, it is impossible to 
obtain a condition for the distribution of the load such 
as can properly be expected from finished surfaces. In 
one of the designs which has come under notice the 
weight was thrown on the centre of the bearing, as 
shown in Fig. 6. Notwithstanding the bearing-metal 




Fig. 6. 

was as strong as any known to the trade for frictional 
purposes, the test of this design, after some years of 
service, gave positive and decided indications of hollow- 
worn journals, due to the springing of the metal at the 
ends, as would naturally follow from such loading. 
Fig. 7 indicates the result, exaggerated, to which refer- 
ence is made. It may be properly inferred that to ob- 
tain sufficient strength of the bearing to prevent such 
a wearing result of the journals would .require a thick- 
ness of metal much greater than when the distribution 



44 



CAR LUBRICATIOI^. 



of the load is more even or uniform. Other objections 
to this increase of the weight of the bearing will be 
indicated in the chapter on the Cost of Lubrication. 




Fig. 7. 

The prevaiUng practice in the distribution of the 
load upon the journal is that shown in Fig. 8, where, 
on paper, the weight is uniformly distributed over 
the whole top surface of the bearing. The practical 
operation, though, is quite different from this, as will 
be readily seen by an examination of journals which 
have been used in this design of box. Instead of 




Fig. 8. 



a uniform wear, it will frequently, if not generally, 
be found that the journal is worn small either toward 
the inside or outside end, showing conclusively that 
the weight is thrown most prominently in either of 



JOURNAL-BOX CONSTRUCTION, 



45 



these two directions. An analysis of the conditions 
will give sufficient cause for this result. The design 
indicated by Fig. 8 is that used by a number of the 
systems, and as regards the distribution of the load it 
will illustrate the general principle which is now ex- 
tensively introduced in railroad work for this purpose. 
When all goes well, uniform wear of the journal can 
be safely looked for ; but when considering that the top 
of the bearing is an unfinished casting, it is not sur- 
prising to find the load actually taken as illustrated by 




Fig. 9. 

Figs. 9 and 10 ; the conditions shown in Fig. 9 illus- 
trating the effect of irregularly distributed high spots. 




Fig. 10. 



That shown in Fig. 10 may arise from one of two 
causes: ist. When the top surface of the journal-box 



46 CAR LUBRICATION, 

is not parallel with the plane of the top of the bearing 
and the desired line of contact. This may arise from 
bad alignment of the box or lack of sufficient parallel- 
ism in the rough castings. 2dT From a journal worn 
small at the front end. It is evident that the positive 
prevention of the first of these influences would require 
a grade of refinement which present practice cannot 
meet. 

When considering Fig. 9 it should be remembered 
that three (3) points determine a plane, the exaggerated 
roughness of the top of the bearing indicating a possi- 
ble if not a probable condition. With this method of 
distributing the load, as the bearing is held during the 
boring by the top surface and the bottom edges, it is 
best to roughly dress these edges, a, a, making them 
parallel with the surface b so that the bored part will 
be parallel with the top. 

The defective distribution of the load arising from 
lack of good alignment, and particularly irregularities 
in the rough castings, can, of course, be partly overcome 
by finishing the fitting parts, but involving thereby an 
expense which the conditions of the case would hardly 
warrant. It would seem, however, that by the method 
indicated in Fig. 11 the trouble would be alle- 
viated without any increase in the refinement of the 
fitting parts. It will be noticed that provision is made 
to accommodate and meet the two prevailing objec- 
tions to a good distribution of the load, and by finish- 
ing the edges, a, a, parallel with the top surface — the 
grinding of which is quite sufficient, — a more positively 
uniform equalization of the load can be obtained, and 
maintained with whatever changes may take place in 



JOURNAL-BOX CONSTRUCTION. 



47 



the position of the box. It will be noticed that the 
bearing is loaded similarly to the method shown in 
Fig. 6, excepting that it has less than half the length 
there indicated to influence the springing of the ends, 
which would not cause sufficient unequal wear of the 
journal to prove a practical objection. When carry- 
ing the load in this way it is not at all necessary that 
the top of the bearing should be parallel with the top 
line of the journal. 




Fig. II, 

Much stress has been placed on the method of dis^ 
tributing the load, and it is very apparent that it is 
much influenced by the device used for transmitting 
the weight to the journal. Its effect is quite apparent 
in increasing the pressure per square inch on a small 
part of the journal, necessitating the use of an oil of 
higher resistance than might otherwise be used. More 
than this, the effect is to wear the journal unequally, 
and in that way render it unfit to receive a properly 
prepared bearing when it is necessary to renew one. 
As regards the latter objection, if the bearing and 
journal were of equal life, and considering only the 
condition after the bearing had worn to sufficient bear- 



48 CAR LUBRICATION, 

ing surface to carry the load without excessive abrasion 
and resulting heating, it would be of less importance as 
to how the weight was distributed ; but when the jour- 
nal, on an average, outwears some half dozen or more 
bearings, it becomes correspondingly difificult to renew 
the bearings without encountering considerable annoy- 
ance from the condition into which the journal has 
been worn by a load that has not been properly dis- 
tributed. It is hardly strange that under such con- 
ditions delays from, and expense of, hot journals are 
encountered. It is rather surprising that they give as 
good a result as is now obtained. 

With the object of meeting these mechanical de- 
fects, Hopkins applied a lining of soft metal, generally 
lead, to the under side of the bearing, by which it is 
enabled to adjust itself to unequally-worn journals and 
thereby rendering a larger surface for the weight than 
can be obtained when a more rigid metal is placed 
upon the journal. The arrangement, though patented 
at the time, w^as a most excellent one, and has given 
admirable results when properly applied to the bear- 
ing. It also assists in meeting the decrease in bearing- 
surface which arises when a new bearing is placed upon 
a much-worn journal. Care should be taken, however, 
to obtain the proper thickness of the soft metal lin- 
ing; which has been found to be about -^-^ of an inch. 
When more than this is used the lead is forced out at 
the edges of the bearing, and obstructs the free admit- 
tance of the oil between the surfaces, and in other ways 
produces trouble. 

As the Hopkins patent has expired, a description 
of the way in which the lining is done may prove of 



JOURNAL-BOX CONSTRUCTION. 49 

value to those who are anticipating the lining of bear- 
ings. 

The operation is as follows : The bearings are first 
bored. As they are to be treated for lining, they are 
first placed on a coke-fire and allowed to become well 
heated, when they are cleaned with muriatic acid 
and tinned. They must then be warmed again so 
that the tin is in a condition for the lead to adhere 
to it. They are then placed on a mandrel to receive 
the lining of lead. The device for holding the bearings 
during the lining can be made of very simple construc- 
tion. It should be so designed that the bearing can be 
clamped only central with the mandrel, which will make 
the hning of uniform thickness over the bearing. The 
radius of the mandrel should never be more than 3^^ to 
yig- of an inch of the radius of the journal which the 
bearing is to fit. The lead lining should never, how- 
ever, be more than -^-^ of an inch thick; and to insure 
this result, the mandrel for the particular diameter 
should be such as to prevent more than this amount 
between it and the bearing. The quantity of material 
to line bearings with lead, and the present market 
prices, are as follows : 



TO LINE ONE HUNDRED (lOO) BEARINGS. 



Material. 


Amount 

in 
Pounds. 


Cost 
in 

Cents. 


Lead , . 


60 

4 
0.4 


285.0 

70.0 

6 


Lead and tin for " tinning " (half-and-half) 

Muriatic acid 







50 CAR LUBRICATION. 

The labor should not amount to more than two or 
three cents per bearing, as it does not require much 
skill for this work. 

The value of this lining as a bearing metal has been 
stated at figures both high and low, but no reliable 
definite values are at hand. 

As a soft metal, however, it will give excellent wear, 
which point has already been brought to notice in the 
chapter on Bearing Metal. 



COST OF LUBRICATION. $1 

CHAPTER VII. 

COST OF LUBRICATION. 

The representation of journal friction in actual dol- 
lars and cents is, after all, the important part of the 
question of car lubrication. It forms the goal to which 
the results of all the investigations in this branch are 
directed. The question is as to how many additional 
cars will an engine haul, or what reduction can be 
anticipated by the introduction of a new device, or a 
definite grade of oil, or, perhaps, a particular alloy for 
the bearing metal, in the cost of maintaining, satisfac- 
torily, the lubrication of car journals. The efficiency 
cannot always, however, be seen in actual dollars and 
cents, without considering all the departments that are 
influenced. It is sometimes obtained through the re- 
duction of anxiety of those in charge, by a lessening of 
the number of delays to trains, as well as a question 
of accommodation of the patrons. Considerable an- 
noyance arises from heated journals, which are known 
to be expensive items of economy, if such can be, and 
is a true representation, when resulting from the use of 
ill-adapted or cheap material, or even of the design, of 
a small first saving with a large final expenditure. 

Included in the cost of lubricating car journals, a3 
now practised, is the wear of the bearing metal, 
quality and quantity of material used in applying the 
lubricant to the journal, the cost and amount of the 
lubricant, the wear of the journal, and, still more im- 



52 CAR LUBRICATION. 

portant, the cost of the resistance of friction as repre- 
sented in coal consumption. Many of these variables 
are dependent upon the relative location of the line of 
the road to the supply markets, as also the current 
market prices of the articles needed, the importance of 
which is not to be considered here, but rather that of the 
efficiency of the mechanical parts. A combination of 
all these elements is obtainable, giving the resulting 
cost of maintaining the proper lubrication of car jour- 
nals. This is also reducible to a condition representing 
the actual economy of oils of different quality and price, 
which material is varied and experimented with proba- 
bly more than any other single one connected with 
the subject — probably, too, because it is the easiest 
handled. 

To obtain an expression for the cost, let 

B == abrasion in ounces of metal per journal per looo 

• miles run ; 
b = cost of bearing metal per ounce ; 
O — quantity of oil in pounds consumed per journal 

per lOOO miles run ; 
= cost of oil per pound ; 
W^= quantity of waste consumed in pounds per 

journal per lOOO miles; 
w — cost of waste per pound ; 
(7=: coal required expressed in tons per horse-power 

developed ; 
c =: cost of coal per ton ; 
A = wear of axle, diametrically, in decimals of an 

inch per lOOO miles run ; 
a = cost of axle wear, including the item of labor for 
finishing, per lOOO miles ; 



COST OF LUBRICATION-. 53 

J z=. journal resistance in pounds per ton of load ; 
T = load in tons per journal ; 
d =^ diameter of journal in inches; 
d^ = diameter of wheel in inches. 
The horse-power developed due to journal resistance 

would then be, per journal per looo miles 

run, 

lOOO d /X Tx 5280 

—z — X 37 X = horse-power. 

60 d 33000 ^ 

The cost of lubricating one journal, including the 
cost of overcoming friction, would be represented by 
the expression 

2.667^j • Cc/T+£di-Oo-f-Aa-{- Ww = M. 

If it is desired to compare two oils, there is but one 
item, that of the value of the waste, which can be left 
out of consideration/ All the other functions enter as 
elements of the cost. The nature of the oil, however, 
would affect the wear of the axle and bearing, as well 
as the resistance from friction. The axle and bearing 
wear differs but little with two oils, unless there is 
considerable difference in their lubricating powers, so 
that, for comparison, the expression could safely be 
reduced to 

M 2.667CC/T+ Oo 



M' ~ 2.667 Cc'fT-{- O'o" 



by which the relative value of two oils, M and M' , 
would be determined. The object is to give, approxi- 
mately, the values of the several functions entering as 



54 CAR LUBRICATION, 

elements of cost of lubrication, and from them to obtain 
some idea of what car lubrication costs when based on 
what is considered as average practice. 

The coal consumption is determinable through the 
pounds resistance offered by the friction of the journal. 
It should be remembered, though, that it is pounds of 
traction, and when determining the coal consumed it 
should include the losses which take place between the 
boiler and the rear coupling of the tender. It is un- 
fortunate that there is such a wide difference of opinion 
as to the pounds of resistance due to journal friction, 
a variation which could not be accounted for by the 
differences in the methods adopted by the various 
roads of lubricating journals. A close approximation 
for average service can be assumed, and a comparison 
can be made of the difference which would result from 
what may properly be considered about as wide a 
variation as takes place in practice. Most of the figures 
used are those obtained by different methods of test- 
ing, but the only true ones are those obtained from 
accurate dynamometer readings. The latest dyna- 
mometer diagrams show, with an engine of the consoli- 
dation type and with cars of 60,000 pounds capacity 
when running on a level tangent at a constant speed of 
fifteen (15) miles per hour, a resistance of 2\ pounds 
per ton. This was with a heavy freight train, and the 
resistance would probably rise to 3^^ pounds per ton 
for lighter trains. Assuming the weight of the average 
freight train in the United States as 130 tons gives a 
basis from which an average figure can be obtained for 
the cost of overcoming the journal resistance. With an 
average car-load of 15 tons this would give 8| cars per 



COST OF LUBRICATION, 55 

train of 130 tons. With cars having eight journals, this 
would give per journal a load of 3750 pounds. With 3 
pounds resistance per ton would require, from page 20, 
1.82 horse-power per 1000 miles run. This is for each 
journal, while the loss between engine and rear end of 
tender would be about 30 per cent. This would in- 
crease the power, when figured for the unit cost at the 
boiler, to 2.6 horse-power. With coal at $1.50 per ton 
on the engine, and a consumption of 4f pounds per 
horse-power, gives as average cost for the frictional 
resistance per journal per 1000 miles 0.926 cent. For 
comparison, let it be assumed that the oil selected 
is ill adapted to the purpose. For instance, that the 
conditions of the service are such that an oil of a 
resistance of 0.512 pound per square inch would be 
sufficient to meet the requirements, but in its stead one 
with a resistance of 0.652 pound per square inch had 
been previously selected and used. The cost per journal 
would then be 1.20 cents, representing an increase of 
over 27 per cent, indicating at once the advisability of 
selecting that oil which will give the least resistance, 
but which is, at the same time, capable of withstanding 
the maximum pressure obtained. 

Considerable variation will be found in the oil con- 
sumption, due to the different service used for the 
comparison. With passenger trains the high speed 
requires a more thorough oiling to dissipate the large 
amount of heat generated by the resistance of fric- 
tion. With such service this heat must be carried 
off much more rapidly than in freight service, where 
any surplus heating by friction, arising from grit or 
other foreign matter, has more time in which to allow 



S6 CAR LUBRICATION. 

the journal to cool before reaching that state where 
the bearing and journal seize. In passenger cars the 
effect is quite different and requires means for ab- 
sorbing in as rapid a manner as possible any surplus 
heat generated. It would then seem that the differ- 
ence in the consumption of oil in the two cases has 
arisen, not from a desire or necessity to reduce the 
coal consumption, but rather to prevent the annoyance 
arising from hot boxes ; and when this annoyance has 
been reduced or obliterated, it is too often assumed 
that the ideal condition of lubrication has been ob- 
tained. For instance, the oil consumption for passenger 
service has been known to be as high as 2.1 pounds 
per journal per 1000 miles, and as low, in the same ser- 
vice, as 0.55 pound. The first is an average condition, 
while the second is the case of a car that was being 
followed to compare the best results of woollen waste 
against a patented device, and indicates the possibili- 
ties in the way of oil consumption where closer atten- 
tion or more systematic means are applied for lubri- 
cation. To further indicate the variation in oil con- 
sumption upon different roads, two lines were compared 
Vv^here the conditions of the service were as nearly 
equal as could be desired for a comparison. The oil 
consumption per journal per 1000 miles was, upon one, 
0.354 pound and, upon the other, 1.05 pounds. From 
this, the difficulty of obtaining an average figure will 
be understood. We will, for an example and an ap- 
proximation, assume it as one (i) pound per journal 
per 1000 miles in passenger service, and as 0.37 pound 
for freight cars. In the ratio of their relative mileages, 
this would give an average- consumption of 0.5 pound 



COST OF LUBRICATION. 57 

of oil per journal per looo miles. At 2\ cents per 
pound, 1.25 cents would represent the value of the oil 
consumption. 

When considering the question of bearings, a very 
pretty point of economy will be found. The nature of 
it is such that it can be and generally is overlooked, 
while its influence upon the cost of meeting this branch 
of the subject will be seen to be an important one and 
influencing quite as much the cost of the bearing as that 
of the metal abraded. It will be noticed that bearings 
are removed from service for two general reasons : 
first, where they are defective from overheating, or 
where they have become too thin from wear ; second, 
from such defects of parts as require the removal of 
the axle. The second includes defective wheels or 
journals. In the first case the bearings may be fit 
for the scrap-heap but nothing better, while under the 
second heading the bearings may be comparatively 
new or but partly worn out. In fact, it will be found 
by an examination of a number of bearings removed 
from service, especially where the hard metals are used, 
that an average life of the bearings would not give 
more than from one half to two thirds their total wear- 
ing thickness as having been abraded before removal. 
The weight of metal remaining is seldom fit for further 
service, so that the loss, representing the difference be- 
tween the first and the scrap value of the remaining part, 
must enter as an element of the cost of the abraded 
metal. For example, taking a bearing which costs to 
produce, labor and material, 16 cents per pound and 
weighing 10 pounds, would give as a total value of 
the bearing $i.6c. To compare extreme conditions, if 



58 CAR LUBRICATION. 

two ounces are worn away in one case and eight pounds 
in the other, the value of the abraded metal, rating the 
scrap as one half the original value, would be as follows : 
where two ounces is abraded, the value of abraded 
metal at $6.48 per pound, and where the eight pounds 
is worn away, a cost of 18 cents per pound. The lat- 
ter would also give a greater average mileage per ounce 
of wear, as this becomes less rapid as the bearing be- 
comes better seated to the journal. This is an extreme 
case, however, and in the absence of positive informa- 
tion we can safely assume, for approximate figures, the 
average condition as that where the bearing has worn 
fifty (50) per cent of its total weight. The first weight 
will be assumed as ten (10) pounds at a cost of sixteen 
(16) cents per pound. This would give the ounce value 
of the abraded metal as 1.5 cents. The wear per jour- 
nal per 1000 miles is about 0.75 ounce, the value of 
which would be, on this basis, 1.12 cents. Objection 
may be raised to the rather low percentage of wear 
which is taken as the amount of abrasion of the bearing 
before removal from service, but it is thought that an 
examination of a number that have been reduced to 
scrap will be convincing. While the percentage of 
wear is low, it is not very far from the average results 
obtained. In fact, this point is such an interesting 
one that it is desired to continue it further. Take, 
for instance, the practice of using a cast-iron shell and 
filling it with a soft or so-called white metal. To elim- 
inate the difference in the cost of the metal used for 
abrasion they will be assumed as of the same value, but 
instead of the bearing containing ten (10) pounds we 
will take it as consisting of seven (7) pounds of abrad- 



COST OF LUBRICATION, 59 

ing metal, five (5) pounds of which, as with the soHd 
bearings, is assumed as worn away before removal. 
The value of the abraded white metal would be 1.2 cents 
per ounce, and for the hard metal, as before, 1.5 cents per 
ounce. The cast-iron shells are practically indestructi- 
ble. The cost of refilling a shell with soft metal would 
be less than the expense of moulding the hard metal in 
sand. To go still further, let it be assumed that both 
bearings, as ready for service, are of the same weight, 
and that the cast-iron shell of the one weighs three (3) 
pounds. Assuming the same weight added to the 
hard metal for strength, this would represent, with cast 
iron at two cents per pound and for an equipment of 
50,000 cars, an increased capitalization of $152,000 
more than where the cast-iron shells and white metal 
are used. It should be understood tliat this represents 
the increased outlay which is necessary for equipping 
with the hard metal bearings, but does not include 
the reduction of the value of the abraded metal, nor 
the less cost of preparing the shell with soft metal bear- 
ing for service. A more detailed comparison of the 
two kinds of bearings would show still further in favor 
of the soft metal, and the argument would indicate 
the advisability of such for car service. The so-called 
wedge or linen which is used over the top of the bear- 
ing in the Master Car~builder's design of box may be 
considered a step in this direction. 

The we:ir of axles will depend much upon the ser- 
vice, w^hether passenger equipment of the different 
kinds or under freight cars ; but when the axles are 
made of steel, and with wheels 33 inches in diameter, 
the wear is found to be about 0.0014 of an inch per 1000 



6o 



CAJ^ LUBRICATION, 



miles. This figure is an average of a number of axles 
under passenger-equipment cars. Axles weigh some 
375 pounds when- new, which, at a cost of 2 cents per 
pound, would be $7.50. Adding to this the labor of 
turning and preparing for service would make the first 
cost about $8.50. With an allowable diametrical wear 
or a diametrical reduction of one half (|-) an inch re- 
duces the weight of a 4X8 journal fifteen (15) pounds, 
and a scrap rate of one (i) cent per pound would give 
the value of the axle wear per journal per 1000 miles 
as 1.372 cents. 

The quantity of waste required per journal-box 
averages 1.349 pounds, from which an approximate 
average of 30,000 miles is obtained, representing, at Z\ 
cents per pound, i\\ cents as the value of this material, 
to which should be added the cost of the oil used in 
saturating the waste, as this is generally thrown away 
with the waste when the latter is removed. The 
amount of oil necessary to saturate the waste for one 
box is 8.4 pounds, which, at a rate of 2\ cents, would 
make the total for the waste and the oil 32I- cents, or 
1.083 cents per journal per 1000 miles. 

To summarize we find as follows : 



Per Journal per looo Miles. 



Coal required in overcoming journal friction . 

Lubricant 

Bearing metal 

Axle wear 

Waste and oil used in packing boxes 

Total 



Cost 


a Cents. 





.926 


I 


.250 


I 


.120 


I 


.372 


I 


.083 



5-751 



It should be remembered that the coefficient of fric- 
tion and the consequent coal consumption are dependent 



COST OF LUBRICATION, 6 1 

Upon the nature of the service, and will be affected by a 
number of elements, such as the load carried, the nature 
of the bearing metal, and the oil, together with other 
minor influences which have been mentioned under their 
respective headings. So, too, the item representing the 
oil consumption is dependent upon the grade of such 
material, as well as what, in the judgment of the person 
in charge, is considered necessary for good lubrication ; 
and is also influenced, to a large extent, by the design 
and degree of maintenance of the journal-box. 

Lately there has been a tendency to substitute a 36- 
inch wheel for those 33 inches in diameter, especially 
in passenger service. The small additional cost, all of 
which is included in the increased weight of iron, is 
more than balanced by the less wear and tear of the 
wheel, resulting from a less number of revolutions, so 
that the work of friction can be considered as reduced 
to an extent equivalent to the proportionate increase 
in diameter. This would affect the coal consumption, 
together with the wear of the bearing and axle, in each 
of which a proportionate decrease can be looked for. 



Per Journal per 1000 miles.— Wheels 36 inches diameter. 


Cost in Cents. 


Coal consumed in overcoming journal friction 

Lubricant 


0.849 
1.250 

1.027 
1.258 
1.083 


Bearing metal. ...» 


Axle wear 


Waste and oil used in packing boxes 




Total 


5.467 





As regards lubrication, the 36-inch wheel is 5 per 
cent cheaper than one of 33 inches diameter. 



^2 CAR LUBRICATION. 



CHAPTER VIII. 

HEATED JOURNALS. 

If a journal becomes overheated, it is positive indi- 
cation that some part of the mechanism is out of order, 
just as with the human body any sickness is proof 
positive that one or other of the organs is not perform- 
ing its proper function. The moral effect in the two 
cases is also similar ; for no one points with pride, un- 
less it be on a competitive line, to a car that is passing 
and leaving behind it a streak of red flame and heavy 
obnoxious smoke from one or more journals that have 
become hot. 

It occasionally happens, and but occasionally, that 
journal-boxes receive too much care. This is apt to 
arise with trains in heavy service and in which delays 
attract unusual attention. With such trains it has 
been known that too much care has been used in the 
attention given to the boxes, especially in the too 
frequent use of new waste. 

The examination of a bearing that has been removed 
from an overheated journal will seldom give sufficient 
trace of the cause. No attention should be given to 
the scaling found on such bearings, as it is simply a 
result and seldom indicates anything more than that 
the bearing has been in contact with the journal and 
heated by the friction so produced until the scaling 
resulted. 



HEATED JOURNALS, 63 

The cause of most of the hot boxes can be reduced 
to two general headings. 

1st. Those produced by mechanical defects. 

2d. Those due to defective lubrication. 

The first is of such a nature that the construction 
can generally be analyzed and corrected. It may be 
in the design, such as the method of distributing the 
load, or imperfect dust and oil protection. Or it may 
arise from poor quality of bearing metal, waste, or oil. 
These as such require the proper course for their elimi- 
nation, although a slow process, and sometimes an ex- 
pensive one, where the lack of proportion or design is 
intricate. It sometimes occurs that the objectionable 
feature can be obviated by the expedient of some 
mechanical turn, such as using a lead lining where the 
load is not well distributed. One case is known where 
are-designed journal-box which became necessary from 
more severe service gave a remarkable reduction of 
heated journals. The percentage of old and new 
journal-boxes in service was about in the ratio of four 
(4) to one (i) ; while the number of heated journals 
arriving at a specified point within a given length of 
time gave the respective ratio of one hundred (iCK)) to 
three (3), giving a difference of ninety-seven (97). 

Heated journals have been known to have occurred 
from a steady and heavy application of the brakes, re- 
ferring to those applied by compressed air. When 
tracing this cause of heating it will be found that a new 
bearing, or one the radius of which is considerably 
larger than that of the journal, was used, and the 
amount of clearances between the pedestal, journal- 
box, and for the bearing is such that a slight raising of 



64 CAR LUBRICATION, 

the bearing results from the journal-box pressing 
heavily upon one side of it. In this way, the edge of 
the bearing is thrown against the journal, when all the 
pressure is taken by a very small area; and, if the 
brakes are kept on for sufficient time, more or less 
heating, but not always a severe condition, will result. 
It is not uncommon for heating to occur from the long 
fibres of new waste working between the bearing and 
journal, and especially before the bearing has worn 
down to its whole arc of contact. 

Under the second head are included those arising 
from the use of poor quality of oil or waste and those 
that are due to improper attention. These arise from 
the lack of sufficient oil for lubrication, but more par- 
ticularly where the waste next the journal has become 
so deteriorated from foreign matter or other means as 
to prevent good lubrication. The pasty condition of 
the top of the waste, more particularly where the ani- 
mal oils are used, is also due to their oxidation and 
their effect upon bearing metals, the extent of which 
was indicated in the chapter on Bearing Metals. 

The preventive for heated journals, coming under 
the second heading, would be a systematic method 
of attending to the lubrication. By this is meant 
that after the car had made a specified mileage, re- 
move the waste from the boxes, which, instead of 
being thrown away, can be cleaned and thoroughly 
saturated with oil, when it will be ready to be again 
placed in boxes for lubrication. The important point 
is to break up the hard, gummy surface which forms 
on the top of the waste, and this can only be accom- 
plished by removing the waste from the box. It is 



HE A TED JO URNALS. 65 

probably safe to say that the method of attending to 
the lubrication of car journals on most if not all of 
the railroads of the country to-day is about as follows. 
The boxes are packed and oiled when the car first 
leaves the shop. After it is in service it is occasionally, 
or it may be frequently, oiled ; by which is meant the 
front of the box is opened and a small amount of oil 
is poured in upon the top of the waste at the front of 
the box. The box is allowed to run in this way, and 
with the little additions of oil, until it is removed for 
one of three causes : a renewal of the bearing or of the 
wheels, or for a heated journal. The top of the waste 
in the mean time has become saturated with foreign 
matter, making a pasty condition which is aggravated 
where the animal oils are used on account of their oxi- 
dation, and probably more or less from the action of the 
acids upon the bearing metal. This condition of the top 
of the waste not only acts as a poor lubricant next to 
the journal, but prevents the oil at the bottom of the 
box from reaching the journal. Of the fresh oil poured 
into the box from time to time, a small part is retained 
by the waste, but a hasty examination will indicate that 
a large part is lost and thrown upon the ties. It has 
often been thought that a systematic method of remov- 
ing the waste, so as to break this hard or pasty sur- 
face, would prove a very profitable investment. If the 
waste, after cleaning, contains too much grit or foreign 
matter to prevent its further use, let the oil, which in 
car service is never what is called worn out, be extract- 
ed from the waste and re-used, thoroughly cleaning it 
and straining to remove foreign matter. 

Until more uniformity in the design of journal-box 



66 CAR LUBRICATION, 

and handling of freight cars could be obtained than 
now exists, the above would, of course, apply only to 
passenger-equipment cars. 

It should be remembered that poor lubrication is 
represented in cost by actual dollars and cents, the 
extent of which is shown in the chapter on Cost of 
Lubrication, and the value of which is there shown to 
be of no small amount. 

Like many troubles, a large percentage of the hot 
boxes could be prevented by the proper application of 
a handful of oil, provided such is done before the sur- 
faces of the bearing or journal have become injured. 

The present method of lubricating car journals is by 
no means an imperfect one when the best is made of 
it, and we should refrain from attributing the failures 
arising from a lack of proper attention to the method. 



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